1. Field of the Invention
The invention relates to the subject that is characterized in the claims, i.e., a portable flow model for simulating ultrasound studies, especially for simulating contrast medium-supported studies.
2. Background Art
As early as the late 1900s, teaching models for practical imparting of a wide variety of diagnostic and therapeutic methods in medicine were produced and marketed. Specifically in the area of diagnosis, such demonstration and practice models still provide valuable support in learning various study techniques.
Sonography represents a valuable aid in studies of the vascular system. For the study of liquid-filled spaces, such as cardiac vessels or blood vessels, however, in sonographic studies in the B-image it is necessary that an echogeneic substance, whose scatter coefficient is significantly higher than that of the blood plasma, be added to the system. Since the scatter coefficients of gases in liquids are especially large, suspensions that contain fine gas bubbles are known as very effective ultrasonic contrast media.
The use of such contrast media offers, however, not only advantages in the B-image but also in color Doppler or spectral Doppler when working under adverse acoustic irradiation conditions.
Since ultrasonic contrast media have been available on the market only for a short time--the first approved ultrasonic contrast medium was actually introduced on the market only in 1991 (Echovist(.RTM.); Schering AG)--awareness of the advantages that are gained when using ultrasonic contrast media is still slight. There is a requirement to provide a device that
makes the physician familiar with the application of these new methods and the resultant new expanded diagnostic possibilities, PA1 shows the advantages of contrast medium-supported sonography, PA1 makes transparent the physical effects that are used, PA1 makes possible comparisons between various contrast PA1 media under standardized conditions. PA1 can simulate pathological alterations of the vessels (such as, e.g., vascular constrictions by "plague" deposits), PA1 can simulate various penetration depths in the tissue.
In the publication by Ilmar A. HEIN et al. (1992) IEEE Transactions on Biochemical Engineering Vol. 39, pp. 1111, a flow model for simulating ultrasound studies is described. In this case, predetermined flow rates of venous and arterial blood vessels are simulated. The latter is achieved by simulating a constant flow or a pulsating flow. The flow model has two pump systems, a peristaltic pump for continuous flow and a reciprocating pump for intermittent flow. The various components of the model are connected together by a tube system that is made of polyester. It is partially immersed in a water bath to control the temperature and to keep it constant. The transducer is also located in a sheathed container in a water bath.
The peristaltic pump provides a constant flow, whereby liquid is pumped into a tall reservoir with an overflow device. Under the action of gravity, the liquid flows from the tall reservoir into a pulsation chamber. From there, the liquid moves into the transducer-equipped study area. If the reciprocating pump is shut down in the pulsating chamber, there is a laminar flow. If the reciprocating pump is active, an arterial flow is simulated. The frequency of the reciprocating stroke is controlled by a motor, which translates rotation into a linear movement using a gear.
The disadvantage is the complicated structure and the use of two pump systems. The reservoirs are also dependent on the flow model being positioned on a horizontal surface. The structure of the reservoirs keeps the flow model from being transported easily.